February 15, 2014

1 - During dry winters some plants do not need irrigation, others will need some supplemental moisture.

Yard and GardenFebruary 15, 2014

Q.

It has been well over a month since the last snow storm. The soil seems to be drying and I was wondering if I need to water my plants. Do plants need to be watered in the winter?

A.

At the time of writing this article, New Mexico has been experiencing the typical dry winter weather. Many plants will survive New Mexico winters without irrigation, especially if there is at least some precipitation. However, some supplemental irrigation is helpful for all but the most drought tolerant plants. Plants native to lower elevation regions of New Mexico rarely need winter irrigation. Desert willow trees do best with no winter irrigation.

Spring flowering bulbs and herbaceous perennials often need irrigation, especially in late winter. As these early flowering plants begin growing in late winter moisture is needed to produce good flowers and tall flower stalks. Without adequate water the plants may flower, but the flower stalks may not develop to full height resulting in flowers touching the ground.

Many evergreen trees and shrubs need winter moisture. Since they still have leaves in the winter they continue to transpire water into the atmosphere. This water needs to be replaced. Broad leaf evergreens such as hollies and boxwood shrubs need more irrigation than needle-leaf trees. Pines and junipers will usually survive well without winter irrigation.

Deciduous trees have lost their leaves, but since most of those we grow are from geographical regions with significant winter moisture, they often need good precipitation or irrigation on a monthly basis. They may survive without irrigation, but their growth and health are often improved by winter irrigation. When you see the buds on these trees swelling in late winter, you should irrigate if there has been little or no precipitation. Although swelling buds do not indicate imminent growth, they do indicate increased metabolic activity in which the buds are manufacturing hormones that will stimulate new root development. If the soil is dry when the new roots form, the roots will die and not be available to supply moisture to leaves and stems that will develop one to two months after the buds begin swelling.

Always consider the importance of balancing maintenance of plant health with the need to conserve water. Although we did receive some precipitation in the autumn, most of New Mexico is currently experiencing abnormally dry to drought conditions. Water your plants wisely, but also consider water conservation an important part of your landscape management practices. Water plants that must be watered, but do not water those plants that will survive without irrigation.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

Links:

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.